Temporomandibular disorders

Definition
Temporomandibular joint syndrome (TMJ) or temporomandibular disorders (TMD) are a group of musculoskeletal conditions that limit jaw movement and cause pain in the temporomandibular (jaw) joint and surrounding muscles.

Anatomy
The temporomandibular joint connects the mandible bone of the jaw to the temporal bone of the skull. You can feel it move when you place your fingers in front of both ears and open your mouth. The joint's bony surfaces are covered with cartilage and separated by a soft disk that keeps them from rubbing together and absorbs shock from jaw movement. Normally, the joint is flexible and moves smoothly up and down, allowing you to easily talk, chew and yawn.

Causes/associated factors
TMD is most common in people ages 18 to 45. It's more prevalent in women than men. The causes of TMD are unclear, but various factors may be involved. Some types of TMD cause damage to the joint itself. Other factors may contribute to overwork, fatigue, or tension of the jaw and surrounding muscles, including:
injury, such as blows to the jaw or overstretching of the jaw muscles during dental care or surgery
arthritis
habits such as clenching or grinding your teeth or biting your nails
emotional stress, anxiety or depression (Researchers are not sure if this is a contributing factor to TMD or a result of living with the pain of TMD.)
A bad bite was once thought to be a factor in TMD, but recent research doesn't support this. Orthodontic treatments, such as braces and headgear, have also been blamed for some forms of TMD, but studies show this is unlikely. There is also no scientific proof that chewing gum causes clicking in the jaw joint that leads to TMD. In fact, many people without TMD experience jaw clicking.


Signs/symptoms
The symptoms of TMD can occur suddenly or develop gradually. They often improve with time, but may recur. Siginificant, long-term symptoms are rare. TMD symptoms may include:
pain and tenderness of your jaw muscles or joint that may radiate to your face, neck or shoulders
a painful clicking, popping or grinding sound while chewing or opening your mouth
locking of the joint, making it difficult to open or close your mouth
a sudden, major change in the way your teeth fit together
Other symptoms, such as earache, ringing in the ears, dizziness or headache, may also occur.


Diagnosis
Diagnosing TMD can be difficult. The exact causes and symptoms of TMD are often unclear. There's no specific diagnostic test available for these disorders, and similar symptoms may be caused by other problems. Researchers continue to work on defining TMD symptoms so that doctors and dentists can develop simpler, more accurate methods of diagnosis and treatment.
Your doctor or dentist will ask questions about your medical history, including information about previous injuries, illnesses, stress and habits (such as teeth grinding or nail biting). He or she will do a physical exam which includes checking your jaw joints and chewing muscles for pain or tenderness, listening for unusual noises when you move your jaw, and looking for excessive wear on your teeth.

Dental or special TMD X-rays don't typically help in diagnosing TMD. Other X-ray techniques, such as magnetic resonance imaging (MRI, an imaging technique based on computer analysis of the body's response to a magnetic field) or computed tomography (CT scan -- a computer-generated, cross-sectional picture of internal body parts), are usually recommended only when conditions such as arthritis or a fracture are suspected, or you have significant, ongoing pain that doesn't improve with treatment.


Treatment
Conservative treatment
Because symptoms are often temporary and don't intensify, conservative treatment is appropriate for most people. This type of treatment emphasizes self-management and makes no permanent changes in your jaw. Your doctor or dentist may recommend soft foods, gentle massage, appropriate exercises, and application of warm, moist heat or ice packs to the affected area. It's important to rest your jaw, so avoid extreme jaw movements, such as wide yawning, loud singing and gum chewing. Also avoid habits such as teeth clenching and nail biting. Physical therapy may also be helpful.

If necessary, your doctor or dentist may recommend pain relievers such as acetaminophen or nonsteroidal anti-inflammatory medications (ibuprofen or naproxen, for example). Muscle relaxants or antianxiety medications may be used for short periods of time. Tricyclic antidepressants, such as amitriptyline (Elavil, for example) or nortriptyline (Pamelor, for example) may help reduce pain and teeth grinding at night.

In some cases, the dentist may suggest wearing an oral splint (also known as a bite plate, night guard or bruxism appliance) over your teeth to reduce teeth clenching or grinding. Periodic adjustments may be necessary. If the splint causes or increases pain at any time, stop using it and consult your dentist.

Although conservative treatment typically provides temporary relief of pain and muscle spasms, it's not considered a cure for TMD. If these measures aren't helpful, contact your doctor or dentist for other treatment options. You may want to explore behavioral treatment approaches, such as biofeedback, relaxation, hypnosis, stress management, habit reversal or cognitive-behavioral therapy. Specially trained facial pain experts or ear, nose and throat specialists may be helpful in treating TMD.

Aggressive treatment
If your symptoms are becoming increasingly disruptive and conservative treatment does not offer relief, you may want to explore more aggressive treatment options. Keep in mind that surgical treatments are often irreversible and should be considered only as a last resort. It's best to get a second opinion before seeking aggressive treatment.

Arthrocentesis is an outpatient procedure that involves puncturing the joint with a needle and flushing it out with a sterile solution. Then, corticosteroid medications can be injected into the joint to potentially reduce pain and improve joint mobility.

Arthroscopic surgery is designed to flush out the affected joint and remove damaged tissue to potentially reduce pain and improve joint mobility. It's done through an instrument equipped with an optical system that allows the doctor to actually look into the joint. A tissue biopsy (taking a sample for further examination) may also be done.

Arthrotomy is open-joint surgery done to repair or sometimes replace the joint. This type of surgery may be done if you have an associated condition, such as severe osteoarthritis or suspected neoplasm (new or abnormal tissue formation that serves no useful function).
Treatment considerations
Researchers have learned that certain irreversible treatments, such as surgical replacement of jaw joints with artificial implants, may cause severe pain and permanent jaw damage. Some of these devices may not function properly or may break apart in the jaw over time. It's essential to get a second opinion before you have any surgery on your jaw.

Remember, for most people, discomfort from TMD eventually disappears whether it's treated or not. Simple self-care measures often ease symptoms. If possible, avoid treatments that cause permanent changes.


Complications
TMD has the potential to cause:
limitations in your jaw joint's range of motion
persistent TMJ dislocation
secondary degenerative joint disease
chronic pain syndromes
depression

Pregnancy-specific information
Pregnancy is not a risk factor for TMD.

Senior-specific information
Growing older is not a risk factor for TMD.

Prevention
To prevent TMD, reduce muscle tension by eliminating potentially harmful oral habits, such as habitually clenching or grinding your teeth; chewing gum, hard candy or raw, hard vegetables; and opening your mouth excessively, such as yawning. Eating soft foods and reducing stress is also helpful.